1. Field of the Invention
The present invention relates to an electrical connector for a flat-type cable.
2. Description of the Related Art
For an electrical connector for a flat-type cable, such as a flat cable and a flexible circuit board, for example, a connector disclosed in Patent Reference 1 is known. In the connector of Patent Reference 1, a plurality of terminals formed by punching a metal sheet is arranged such that the sheet surfaces are parallel to each other. A latching metallic piece 20 having similar shape to that of the terminals as shown in the accompanying drawing, FIG. 3(A), is provided at the both ends of the arrangement.
As shown in the figure, each latching metallic piece 50 has generally H-shape, and has an upper arm 51 and a lower arm 52, which are connected by a connecting section 53. The upper arm 51 has flexibility to displace upward/downward, while the connecting section 53 works as the fulcrum, and has a latching claw 51A at its front end, and a pressuring section 51B at its rear end. When the latching metallic pieces 50 are inserted from the rear side (right side in the figure) to corresponding slits of the housing 54, each lower arm 52 is securely held by the housing 54. To secure this holding, each lower arm has latching protrusions 52A.
A cam section 56 having an oval surface is formed at each pressuring member 55 and located between the rear ends of the upper arm 51 and the lower arm 52, and contacts with the inner edges of those arms. Each pressuring member 55 makes rotational movement between the open position illustrated in FIG. 3(A) and the closed position illustrated in FIG. 3(B), having the cam section 56 as the center of the rotation. In this connector, terminals which are not illustrated in the figures have generally similar shape as that of the latching metallic pieces. In addition, each pressuring member has a cam section, which is similar to the cam section 56, for the terminals.
When the pressuring member is at the open position as illustrated in FIG. 3(A), the cam section is horizontally long, but once the flat-type cable F is inserted from the left side, the cable contacts with the contact section which is at the left end of the terminal, and then moves to a specified inserting position, while lifting the contact section. When each pressuring member is rotated to the closed position as illustrated in FIG. 3(B), and the cam section is moved and turned to be vertically long, the cam section 56 displaces so as to lift the right end of the upper arm of each terminal. The cam section that corresponds to each terminal also similarly displaces. As a result, since the cable does not have a latching hole to receive the left end of the upper arm of each terminal, the left end of the upper arm works like a lever and is deformed downward so as to increase the contact pressure to the cable.
As shown in FIGS. 3(A) and 3(B), the flat-type cable F has latching holes F1 for the latching claws 51A to latch on, corresponding to the positions of the latching metallic pieces 50 that are provided at the both ends of the arrangement of the terminals. Similarly to the terminals, when the pressuring member 55 is at the open position as illustrated in FIG. 3(A), the cable can be easily inserted. Once it is inserted to a specified position, each latching claw 51A is latched onto the latching hole F1 of the cable F. Then, similarly to the terminals, once the pressuring member 55 is moved to the closed position of FIG. 3(B), the right end of each upper arm 51 is lifted by the cam section 56. Accordingly, the latching claw 51A displaces further downward, and the latching is increased. When the connector is in use, the right end of each upper arm 51 is lifted by the cam section.
[Patent Reference 1] Japan Unexamined Patent Application Publication 2005-078908
In the connector of Patent Reference 1, once the pressuring member is brought to the closed position, each latching claw is securely latched onto the latching hole, so that coming off of the cable is effectively prevented. However, the upper arm 51 of each latching metallic piece 50 always receives a force from the cam section when the pressuring member 55 is at the closed position. When the connector is in use, the pressuring member is at the closed position, and the length of time when it is at the closed position is extremely long. Therefore, the upper arms receive a force for long period of time, and can be damaged by fatigue due to the inner stress.
The connecting section 53 of each latching metallic piece 50 is formed relatively thin and long so as to be flexibly displaced. When each latching metallic piece 50 latches on, stress is applied to the connecting section 53. If a force such as a force to forcibly remove FPC is further applied under such condition, the connecting section may be plastically deformed receiving even more stress.